1. Area of the Art
The present invention concerns the field of medical treatments and more specifically a system for removably attaching a source of heat or cold to a human body.
2. Description of the Prior Art
Most people are almost inherently aware of the medical benefits of local application of either heat or cold. In many cases thermal treatments can have almost miraculous results that surpass those provided by many complex and expensive pharmaceutical agents.
When joints and muscles are traumatized as in a sprain or similar injury, there is great benefit to the rapid application of cold to the site of injury. The lowering of temperature inhibits the inflammatory processes that can actually exacerbate the injury if allowed to run out of control. Low temperatures inhibit the movement and penetration of white blood cells that mediate inflammation. Low temperatures also inhibit the cellular responses to inflammatory molecules that are released at the site of injury.
Other medical problems such as migraine headache also respond favorably to application of cold. In some cases colds is mostly anaesthetic acting by inhibiting conduction of pain signals through the nerves. In many other cases as discussed for traumatic injury the cold is more than palliative. Paradoxically many conditions, including the injuries that are initially benefited by application of reduced temperatures, are later benefited by application of heat. Whereas cold dulls the extreme pain of traumatic injury, heat alleviates chronic pain particularly of joint origin. The explanations for the positive effects of applied heat are, perhaps, even more obscure than those for the application of cold. Generally, applied heat increases the local blood flow. In some cases increased blood flow may be essential for or stimulate tissue regeneration and healing. Much chronic pain is caused by muscle spasms and the like. Applied heat often results in muscle relaxation and a diminution of spasms.
Because of the benefits of thermal manipulationxe2x80x94that is applied heat or cold, there have been a plethora of devices intended to manipulate the thermal status of portions of the human body. Some of these have been fairly complex such as diathermy instruments and related devices that cause localized heating mediated by the application of sonic or electromagnetic energy to the body. However, the majority of such devices have been means to attach a portable source of heat or cold to some portion of the body. Generally, these devices consist of some combination of straps, catches and hook-in-loop fasteners to removably attach a hot or cold pack to some portion of the body. In some cases direct adhesives have been used but there has been a continuing problem with the removal of such adhesive attached thermal treatments. Their removal can damage the skin, or if they are placed over a region having significant body hair, their removal can be painful indeed. In a hospital situation a variety of different solvents may be used to help remove the adhesives, but this is often safe neither for the patient nor the environment.
U.S. Pat. No. 4,517,972 to Finch, Jr. illustrates a multipurpose system for attaching thermal or other treatments. Essentially, the thermal treatment is removably attached by hook-in-loop fastener to patches of traditional adhesive. While this approach allows the ready removal or replacement of the thermal treatment, removal of the adhesive patches still involve the difficulties already mentioned. In particular the device cannot be attached to regions with abundant hair such as the male torso or even the crown of the head.
U.S. Pat. No. 3,871,376 to Kozak describes another thermal dressing employing layers of frozen hydrophilic gel to provide a cooling source. This structure is attached to the body with adhesives of the type xe2x80x9cconventionally employed in the pressure-sensitive tape artxe2x80x9d. The thermal dressing disclosed in U.S. Pat. No. 5,702,375 to Angelillo et al. can be attached to the body by an optional region of xe2x80x9cadhesive meansxe2x80x9d.
Frequently in the prior art the thermal bandage or dressing is applied by means of wrapping (U.S. Pat. No. 4,377,160 to Romaine) or by means of a strap that wraps around a body portion and attaches to itself by means of a loop-in-hook fastener (U.S. Pat. No. 6,017,606 to Sage et al.; U.S. Pat. No. 5,984,951 to Weiss et al.; U.S. Pat. No. 4,854,319 to Tobin; U.S. Pat. No. 4,556,055 to Bonner, Jr.). This may be due to the problems with removing adhesive from or use of adhesive on hairy portions of the body. Further, many adhesives are adversely affected by the temperature extremes and/or wetness of thermal bandages.
U.S. Pat. No. 5,913,849 to Sundstrom et al. has attempted to deal with some of the shortcomings of ordinary adhesives by providing a special liquid-absorbing adhesive layer for use with heat dressings. The hydrogel adhesives of this disclosure are described as comprising discontinuous phases containing an elastomer and a resin. A discontinuous phase of water soluble/water swellable hydrocolloids are dispersed through out the continuous phase. It appears that the major motivation for use of this adhesive type is for treatment of exuding wounds wherein the adhesive absorbs the exuded fluid. Unfortunately, the latex or other elastomer employed is often hard to remove from the skin and can be irritating or allergenic.
The current invention is directed towards an improved means for attaching thermal dressings. A preferred embodiment is a device for ready attachment and removal of an xe2x80x9ccold packxe2x80x9d wherein the cold is produced by one of the widely available salt/solvation devices. However, the present invention is operable using essentially any type of source of heat or cold. Ideally such a thermal source is self-contained and portable for use in first aid treatments; however, portability is not required. The present invention involves a novel adhesive that permits firm attachment of the dressing to essentially any portion of the human anatomy with no need for wrapping completely around the limb or other anatomical region. That is, the device attached to the skin with an adhesive that is sufficiently strong to maintain the device in position against repeated motion. Yet, the adhesive is sufficiently weak that the dressing can be peeled off from the skinxe2x80x94even in the presence of body hairxe2x80x94with essentially no pain.
These results are achieved using a hydrated gel adhesive with little or no intermixed elastomers or xe2x80x9ctraditionalxe2x80x9d adhesives as has been used with hydrated gels in the past. Because the adhesive is hydrophilic and relatively thick and soft, it adheres by molding itself to the skin surface, into irregularities and into and around hair shafts. However, because the material contains essentially no elastomers, it does not grip hair shafts and does not pull strongly on hairs when the dressing is peeled. Further, traditional elastomers contribute to the allergenic properties of the material. The relatively soft hydrophilic adhesive is essentially incapable of pulling on a hair. A traditional elastomeric adhesive attaches to a hair or to the skin by molding itself into crevices and various intricacies. When the adhesive is peeled off tiny bodies of elastomer remain within these crevices and tiny elastomeric bands stretch from the main dressing to these bodies. Ultimately these bans break under tension or the bodies are pulled from the crevices. In this process the skin surface or the hair is painfully tugged. The hydrophilic gel of the present invention adheres by molding itself to the surface, but when it is peeled away, the lack of elastomer causes it to cleanly detach with no painful tugging.
Because the hydrophilic gel adhesive of the present invention operates without a traditional elastomer, it""s xe2x80x9csticking powerxe2x80x9d is essentially completely dependent on the ability of the gel to mold to a surface. If the gel becomes dehydrated, it loses most, if not all, of its power to stick. Therefore, it is necessary to supply the device of the current invention in an airtight impermeable package to maintain the gel adhesive in a hydrated state. Before use this package is opened and the adhesive surface is revealed by peeling back a protective covering similar to that of a normal adhesive bandage. The hydrophilic gel adhesive is preferably formed by coating a suitable gel on a backing of a felt-like non-woven fabric. The gel penetrates into the fabric which serves as a flexible support onto which the thermal portion of the dressing is attached by methods well known to the art. The ideal gel is essentially saturated with water and is sufficiently crosslinked so as to not be dissolved or washed away by additional water. That is, the gel can absorb a small amount of additional waterxe2x80x94as from condensate of a cold packxe2x80x94but the adhesive is not dissolved or washed away. Further, little or no adhesive transfers from the fabric backing to the skin or hair. Suitable gels include polysaccharide xe2x80x9cgumsxe2x80x9d and polyacrylamides and similar acrylic derivatives. The gel can be coated onto the fabric using a suitable solvent which then evaporates leaving the gel permanently embedded in the fabric. Alternatively, the hydrophilic gel can be polymerized into the fabric from monomers. Ideally, the final product is a gel with little or no solubility in water at room temperature so that the gel remains attached to the fabric even if placed in water.